When The Tether Snaps
by starrysummernights
Summary: Sherlock doesn't understand what's happening. One moment, he and John are walking down the street, John unusually quiet, shoulders hunched, mouth thinned down, walking briskly- and the next moment John is grabbing Sherlock and forcefully pulling him into an alleyway. "You smell like him." John growls. "You even goddamn taste like him." Omegaverse.


**Thanks to TheMadKatter13 for this idea. It was a lovely thought :D**

* * *

John stands off to the side in Lestrade's office, hands clasped behind his back, chin thrust out, lips pursed, trying his best to control his temper. He's angry. No, that's not it. He's not just angry.

He's fucking _furious_.

John takes a deep breath, breathing in the coffee and doughnut smells of Lestrade's office, and whooshes it all out in a sigh. He knows he's being unreasonable. Irrational. That knowledge, though, instead of snapping him to his senses and calming him down, just serves to make him even angrier.

"Your recollection of events is _astounding_. You're being of so much assistance to me- may I get you a glass of water? No? Doughnut? You look incredibly pale. You need to eat something." Sherlock chides, voice a soothing murmur in the air-conditioned hush of the office. John's eyes narrow, the tone of Sherlock's voice setting his teeth on edge, anger boiling in his chest until it almost chokes him. His hands, clenched into fists, curl even tighter, his knuckles turning white at the pressure.

"N-No, thank you. I'm fine." Their witness, a distraught Omega male named Jeremey, _clings_ to Sherlock. He sits too close on the leather sofa and holds Sherlock's hand with both of his own, gazing up worshipfully as Sherlock asks him questions in a quiet voice, eyes kind and understanding.

"Are you sure?"

Jeremey's eyelashes flutter as he blushes with shyness, nodding. He's clearly flattered with the attention Sherlock is giving him, even if it's all case-related. Even as John watches, he scoots closer to Sherlock, closing the miniscule gap between them and pressing their thighs together, elbows bumping, chests inches apart. Any closer and Jeremey will be sitting in Sherlock's lap.

"You've been through an incredibly traumatic experience today. Really, I must insist that you eat something." Sherlock replies firmly, the tiniest note of authority leaking into his voice and Jeremey soaks it all in, eyes dipping down again and cheeks flushing darker with pleasure. Here in Lestrade's office, wearing a youthful t-shirt and jeans, his curly auburn hair endearingly mussed, and blue eyes large, liquid, and innocent, Jeremey looks ethereal. Pale and very breakable. He looks incredibly _young_, as if he's not old enough yet to be let out on his own without terrible things happening to him, as if he needs to be protected from the world. Even his scent is soft, delicate, and reminiscent of freshly cut grass and spun sugar. He makes _John_ want to protect him- it's obvious what protective instincts he would inspire in an Alpha.

"All right. I suppose a…a doughnut. Please. Chocolate, if you have them."

"Of course." Sherlock beams approvingly at Jeremey, squeezing his hand, before turning to John. "Fetch a couple doughnuts from the break room down the hall. And a bottle of water." His focus on John is fleeting and dismissive and he's already turning back to Jeremey, face a picture of concern. "After all this talking you must be parched."

John grits his teeth, briefly thinks of telling Sherlock to get his own fucking doughnuts…then takes another deep breath and marches from the room, stiff-legged and fuming.

It's for the case. John knows that. Sherlock's done this before- Omega witnesses always react best to Sherlock. They're soothed by his Alpha scent, his protectiveness, his faux solicitousness. They invariably relax and let down their guard and talk, revealing valuable information that has more than once been the key to solving a case.

John knows that. _He knows that_. He's watched Sherlock do this time and time again and never once batted an eye. He's never cared when Sherlock stroked a pale cheek, thumb caressing gently, and sweetly pleaded with an Omega witness to answer his questions. He's never cared when Sherlock cooed and whispered at them, treated them with courtesy and gentleness because…well, it was for a case. It was a way of getting information. It didn't mean anything.

John knew that.

Then why was it affecting him so strongly this time?

He doesn't even have the feeble excuse that it's close to his heat and his emotions are being hijacked by his changing hormones. That's still weeks away, but even if it were close, even if John were hours from going into heat, he still feels that it wouldn't justify how he feels. He never lets himself use his sodding _hormones_ as an excuse for his behavior.

John's honestly ashamed of how he's acting. He's never wanted to be one of those clingy, possessive Omegas who get ridiculously angry whenever someone so much as looks at their Alpha. He's better than that. That's not who he wants to be. He's spent his entire life eschewing typical Omega manners, tropes, and expectations. He's rallied against them, derided them, and forcefully molded himself into the person _he_ wants to be, not the person society expects him to be because of his biology.

But it seems today that's all gone out the window, went up in flames as soon as Sherlock sat beside the scared Omega on the sofa- the one with the captivating scent and the pretty smile- and took his hand, asking him in a comforting voice if he were able to recount what had happened.

The memory leaves a bad taste in John's mouth.

He grabs the doughnuts from the empty break room but stays in the mercifully isolated little room for a few minutes, giving himself some much needed time to calm down before going back to Lestrade's office. He grips the counter, letting the sharp edges dig into his sensitive palms, using the pain as an anchor, a reminder, a way to try and stop the choking possessive jealousy that's lodged in his chest and won't…fucking…stop.

Jeremey's scared. He just saw his prospective Alpha mate gunned down by masked men- the same men who earlier in the week killed four other people, all of them only vaguely connected, not enough for Sherlock to put everything together and solve the case. Jeremey spent three hours in his own closet, tied up and gagged, before his sister luckily rescued him and he's spent the last few hours recounting it all to Sherlock. Jeremey's frightened. He's vulnerable. He needs sympathy. Understanding. Not useless Omega hostility.

And John's usually able to provide that. When Omegas don't respond to Sherlock, they _always_ respond well to John. They trust him because he's an Omega and that means less threatening and trustworthy and safe.

He just can't today. Not this time.

And he doesn't know _why_.

* * *

When John enters the office again, Lestrade is on the phone, talking quickly and giving instructions while writing frantically on a notepad. There's obviously been a breakthrough in the case and when Lestrade hangs up, he gives John a triumphant grin.

"Bastards'll be apprehended in the next ten minutes. Donovan's going to call me back when they have them." He heaves a relieved, tired sigh. "That was some work, eh?"

John nods wordlessly, lips jerking up in a semblance of a smile, before reluctantly turning to the sofa. Jeremey is leaned against Sherlock, his head resting on Sherlock's shoulder, face buried in his neck, slim hands clutching at the lapels of Sherlock's suit. Sherlock's arm is wrapped around Jeremey's shoulder, patting it gingerly.

The sight hits John like a physical blow. It stings, utterly takes his breath away, and for a few seconds he can't even think beyond the rage the tableau inspires. Then he tightens his jaw. Curses himself out, calling himself eight different kinds of an idiot, and clears his throat.

"Here." He thrusts the food at Jeremey, unable to articulate more. If he does, he'll do something stupid and embarrassing like start shouting.

Jeremey reluctantly pulls away from Sherlock and spares John a brief, grateful smile as he takes the food. "Thank you."

John nods shortly before turning to Sherlock. "Ready?" He asks brusquely, face closed off, trying to act impassive when he's practically vibrating with repressed energy. Sherlock gives him a quick look, a line forming between his eyebrows, before he nods, untangling himself from Jeremy and the very fact that he _has_ to untangle himself makes John see red.

"M-Mr. Holmes."

Sherlock pauses, looming over him, and Jeremy scrapes his teeth over his bottom lip, gazing speculatively up at him. There's blatant interest in his gaze as his eyes flick up and down Sherlock's body.

"Thank you. For everything. You've been so kind to me. And…I- I was wondering….it's just…well, if you're free….maybe you'd like to have dinner with me?"

It's the outside of _enough_ for John. Everyone here can goddamn _smell_ Sherlock is bonded. Jeremey, pressed against him for hours, couldn't have failed to notice the obvious scent. John experiences a brief flash of longing, wishing he'd worn a more open collared shirt so his bond bite would be noticeable. He'd love to see Jeremey's face when he saw the ravaged scar, still healing. It's noticeable, overt, and inherently possessive.

Then he shakes himself. He's never wanted that before. _Ever_. He doesn't want it now. What the hell is wrong with him?

"I'm sorry. I'm happily bonded and not interested in an affair. Thank you for the information." Sherlock gives Jeremey a dismissive smile, pulling on his gloves, and nods at Lestrade.

"Wait- Sherlock, we're not done- I need you for the paperwork-"

He's ignored and John and Sherlock are out the door, and crossing the busy landscape of cubicles. John walks as fast as he can, Sherlock a steady presence beside him. He punches the lift call button, shoving his hands in his coat pockets to keep from doing something stupid- like pulling Sherlock against him and snarling that Sherlock is _his_.

Sherlock's looking at John from the corner of his eye, his gaze an almost tangible weight against John's skin, assessing. "What's wrong?"

"Nothing." John bites out tersely, getting in the lift and punching the bottom floor button. "Nothing's wrong. I'm fine."

"You don't look fine." Sherlock says slowly, knowing something is wrong but unable to comprehend what exactly, for which John is grateful. He doesn't want Sherlock to know how petty and…wrong he's being.

"I'm fine. Really. Just…tired." He sniffs, shrugging his shoulders, rolling them in their sockets to ease the collected tension there. "Been a long day."

Sherlock obviously doesn't believe him but he knows John and he knows not to press the issue. They're quiet during the ride down, while crossing the bustling lobby and out onto the crowded, loud street. John breaths in the pollution clogged air, trying to clear his head and quieten the monster lurking in his chest.

It's fine.

When they get back to the flat, Sherlock will shower and change his clothes. He'll wash away the nauseating smell of the Omega that clings to his person. He'll tell John all about the case. John will type it up on his blog. They'll have sex, preferably on the new rug in the sitting room. Then the possessive jealousy that's lodged in John's chest can fade away and will become a distant memory.

It's fine.

It will be fine.

But at that moment, the breeze picks up, blowing Jeremy's scent, rolling off Sherlock's body and mingling with his own scent, full in John's face.

And he snaps.

* * *

Sherlock doesn't understand what's happening. One moment, he and John are walking down the street, John unusually quiet, shoulders hunched, mouth thinned down, walking briskly- and the next moment John is grabbing Sherlock and forcefully pulling him into an alleyway.

Sherlock flounders, caught off guard, grabbing onto Johns arms as he's roughly maneuvered further down the alley and shoved up against the rough brick. He's still trying to get his wits about him- a senseless part of his brain wondering if John is saving them from an attack- when John buries his face in the bend of Sherlock's neck, inhaling deeply.

Sherlock's mouth goes dry and his fingers spasm, digging in where they're already gripping John. It's not that John _never_ scents him…but it usually only happens during John's heat, never between times, and the novelty of the action makes him immediately hard.

"You smell like him." John's rough growl reverberates against Sherlock's throat and Sherlock's cock gives a traitorous, hard throb.

"Smell like…who?"

John doesn't answer, taking another deep inhale, his tongue coming out to lick a wet line from Sherlock's neck to his ear. "You even goddamn _taste_ like him." John presses closer against Sherlock, as if he's trying to meld their bodies together. "Fuck. You smell like him. Taste like him. Goddamnit, Sherlock." John rests his head against Sherlock's shoulder, breathing hard, practically panting, his body a rigid line against Sherlock's. "Why?" He asks, voice low and vibrating with tension. "Why, Sherlock? Goddamn fucking _why_?"

"I…" Sherlock licks dry lips, piecing together what has John so angry- obviously, Jeremey and the way Sherlock acted around him but…John's never acted this way before in response to Sherlock's manipulating Omega witnesses. Sherlock doesn't understand what's provoked this reaction now and he struggles for a way to fix it. "It…it was for the case, John. I didn't mean any of it- you know that-"

"I know." John raises his head and even in the dark of the alley Sherlock can see the annoyed set of John's face, his eyes heavily dilated. "I know it was all for the case. For show. And do you know why, Sherlock?"

Multiple answers spring to mind, each plausible, but Sherlock shakes his head, knowing John has the correct answer.

"Because you're _mine_." John snarls, roughly jerking Sherlock forward and kissing him, crushing their lips together and invading Sherlock's mouth with his tongue. Sherlock shudders, a delicious tingle running through his entire being. John has never once said that, never articulated his control- his possession- of Sherlock and Sherlock's heart is thrumming from hearing it finally verbalized. He feels positively light-headed.

"You're mine." John breathes into Sherlock's mouth and Sherlock fervently wants to say yes, of course he is. He's _always_ been John's, ever since that first meeting at Bart's, long before there was ever the smallest hint of their being more than friends. He wants to tell John that he belongs to him in a fundamental way that goes beyond things like Alphas and Omegas and bond bites…but John is kissing him again, fucking into his mouth with his tongue and Sherlock moans, lets John do whatever he wants, the words _"you're mine"_ echoing around his head in John's voice.

John tangles his fingers in Sherlock's hair, proprietarily pulling at it, tipping his head to the side as he kisses him, grinding his thigh hard against Sherlock's cock. Sherlock whimpers, his erection jumping under the pressure, aching, and he ruts forward, rubbing his hip against John's own hardness. He clutches desperately at John, at any part of his body he can get his hands on, kissing him frantically, their lips smearing messily together. John untangles his hands from Sherlock's hair and cups Sherlock's face, palms warm, a suggestion of tenderness amidst the callous roughness. Sherlock leans into the touch, breath huffing out, sounding loud in the relative quiet of the alley.

"I want you to fuck me. Right now."

Sherlock wonders where his John has gone- his sweetly dominant, John- as he struggles for coherent speech. "Yes." _Whatever you want. Of course, always, whatever you want._

"Then get me ready." John instructs heatedly and in no time Sherlock finds himself on his knees, uncaring of the grit grinding into the legs of his trousers, John's jeans and pants down around his knees, his hands shaking as he spreads John's arse, licking him open. It's not close to John's heat, more's the pity, because then John would be a little wet when he's aroused, wet enough to be fucked. But he's not, and neither of them thought ahead to bring lube. It's a mistake Sherlock will never make again.

They have to make do with what they have and so Sherlock devotes himself to preparing John, licking at his tightly closed hole and hurriedly opening him up with his tongue and fingers, aware that they could get caught in the alley at any moment. John groans and pushes back against Sherlock's face, fisting his cock, making small little noises he tries to muffle against his arm. Sherlock uses as much saliva as he can, pushing it into John's arse with his fingers, wanting to make him soaking, not wanting to hurt him….but too soon John is pulling away, turning around and pulling Sherlock up, fumbling at Sherlock's belt.

"You're not-"

"This is how I want it." John silences Sherlock's protests, pulling him out of his trousers and giving his cock a hot, blistering stroke, rubbing at the leaking tip of his cock, smearing the wetness around the crown teasingly.

"_God._" Sherlock's head falls forward, shuddering, but John pushes at him, taking his hand away and Sherlock quickly grabs John, hoisting his legs up and around his waist. John loops his arms around Sherlock's neck, arching, trying to help as Sherlock fumbles beneath him, trying to thrust himself inside. He misses….and misses again. Growling in frustration, Sherlock hoists John higher, pressing him against the unyielding brick wall and using that as leverage to keep him up as he reaches once more, the head of his cock finally catching on John's rim-

Sherlock sobs, the tightness and heat of John's body tantalizing, incredibly enticing. He tries to go slow, careful, not wanting to hurt John- but John bucks his hips, almost unseating Sherlock, forcing him to readjust his grip and gracelessly shove himself inside to keep from losing the contact.

They both gasp, one high and shocked, the other slightly pained and John's arms tighten around Sherlock's neck as he starts thrusting, hard and mindless, John panting in his ear.

"You're _mine_." John growls before yanking Sherlock's hair, forcing his head back at a sharp angle. Sherlock tremors when he feels the _delicious_ scrape of John's teeth over his jugular and anticipation spikes, hopeful and aroused, in the pit of his stomach. "You're fucking mine, Sherlock. Mine….mine…mine." Each word is breathlessly punched out of him by a bruising thrust, Sherlock's hips moving quickly in the space between John's legs, his eyes closed against the rising pleasure.

"_Yes_." Sherlock's voice is strained from the angle and breathy.

"Say it, Sherlock." John's teeth nip hard at Sherlock's throat and Sherlock's hips stutter, breath catching in his throat. He desperately wants to tell John to stop doing that, if he keeps it up Sherlock will come. His orgasm is already there, hovering at the edges. It wouldn't take much. Luckily, John's hand loosens in his hair, allowing Sherlock's head to fall forward again and he's pulled down into a kiss. "Say it. Fucking. Say. It."

"I'm yours." Sherlock gasps, jamming himself into John faster, arms starting to burn from holding John up, his legs sliding on Sherlock's waist, slippery with sweat. "I'm yours. I'm your….your Alpha-"

"Yes. You're _my_ Alpha." John echoes, hands digging into Sherlock's arms and rocking his hips as much as he can into the punishing thrusts. He pulls Sherlock closer and it makes it harder to thrust, Sherlock can only just rock into John's body, but it still feels amazing. Feels like heaven. Like coming home.

"Oh…oh, fuck- Christ, Sher…lock…wish you could fucking knot me."

Sherlock's so shocked at John's words that he freezes, his cock buried in John's arse, throbbing with the sudden denial. He can't have heard John right. It's not possible. John would never, ever say something like that. He hates silly, Omega phrases like that. He told Sherlock so the very first time. He hates it.

"Don't stop- Oh, Christ, don't fucking stop!" John groans agitatedly, tugging at Sherlock in an effort to get him moving again. "…Oh, god, yes." John gasps when Sherlock starts thrusting again, still stunned but desperate to please his Omega.

"Fuck….Mine…Oh, Christ. Bloody- mine." John tips Sherlock's head to the side again, his lips dragging over the clammy column of his neck. Sherlock shudders in John's arms, tensing, hope warring with trepidation over what he thinks- hopes- John's about to do.

"Mine." John mutters one more time, before he bites. He sinks his teeth into the soft, pale flesh of Sherlock's neck, the first time he's ever- in the entire time they've been bonded- marked Sherlock's body in any discernible way. Sherlock chokes, too stunned to keep moving. Everything coalesces in his body, eyes widening, at the shocking truth of what John's doing- marking him, claiming him. It's what Sherlock's wanted for months and months, his Omega marking him as his own-

Sherlock shouts, the sound agonized and ecstatic, as he unexpectedly comes. Powerful, thick pulses wrack his body, ripping through his nerves as he empties himself into John, leaving him wringed dry. He cries out as John releases his neck with a filthy, wet sound. John's cock is trapped between them, still hard and leaking, and Sherlock reaches down to stroke it-

"No- no, let me down." John commands anxiously, wriggling, and Sherlock has to drop his legs where he's been holding them rucked up. John's feet hit the gritty concrete with a rough sounding thud and he quickly turns around, his jeans still down around his thighs, Sherlock's come leaking from his arse, and braces himself on the wall, hands splayed against the brick.

"Like this." He says and Sherlock frowns, wobbly and slow from his orgasm, from John marking him, still not understanding-

John's head falls to the side, his neck a sliver of white in the darkness, baring his bond bite in a classic Omega pose, offering himself to Sherlock.

Sherlock falls on him with a needy whine, reaching around and grasping John's cock. He tugs at it as his teeth sink into John's neck. John's hips thrust needily into Sherlock's hand, pained little gasps falling from his lips as he bucks repeatedly, whining. Sherlock strokes at his cock harder, sinking his teeth deeper, worrying a bit at the skin and John tenses right before his release soaks over Sherlock's hand. He judders in Sherlock's grip as he comes, body convulsing, before going still against him.

Sherlock's legs are shaky, his knees knocking, and he doesn't think he'll be able to stand much longer. He carefully releases John, licking once over his bond bite, before bringing his hand to his face, licking it, cleaning it of John's ejaculate. He offers John his handkerchief when John wearily turns around and he accepts it with a strangely resigned sigh, his eyes averted.

A frisson of fear snakes its way up Sherlock's spine at John's expression. He silently watches as John sets himself to rights, tossing the soiled handkerchief to the side and doing up his jeans.

"Sherlock…I'm sorry." John mutters, looking anywhere but at Sherlock. He purses his lips, sighing heavily again. Embarrassed. "I'm so sorry. I don't honestly know what came over me."

Sherlock secretly hopes whatever it was comes over John more frequently, but keeps his mouth closed.

John clears his throat. "After watching that today…back there…I just…couldn't help it. I don't know why." He shakes his head, clearly disappointed with himself and uncomfortable. "I didn't hurt you, did I?"

"Of course not." Sherlock lies. He's never been bitten before and his neck _hurts_. It stings, heralding the throbbing pain he knows will come later, and he wants nothing more than to be curled up on the sofa, John wrapped around him or sitting at the end holding his feet, when it starts full force. He won't even take a paracetamol, he decides with a pleasant little shiver. John has never marked him before and he wants to relish the pain while he can, doesn't want any distractions to detract from the pleasure of this rare occasion. He hopes it scars. It won't be a bond bite, obviously, but it's close enough.

"I'll fix you up when we get back to the flat." John promises as they slowly make their way out of the alley on shaky legs.

"Not necessary. I'm fine."

John eyes Sherlock's neck, the bite livid against his pale skin, still oozing beads of blood that drop down onto the collar of his shirt. His lips tighten, eyes going clouded. "Somehow I doubt that. Christ- I'm so s-"

"Did you really mean it?"

"Mean what?"

"That I'm…" Sherlock trails off, unaccountably nervous. John loves him. They're in a bonded relationship. He shouldn't be worried about asking this question.

"What?"

"That I'm _your_ Alpha."

John stares up at Sherlock for a few seconds, his usually easy to read face suddenly a mystery to Sherlock. It's as if all the lines and planes have suddenly rearranged themselves in the space of a heartbeat and Sherlock doesn't understand them. Not anymore.

"It's fine." Sherlock quickly says, throwing up his hand as he sees a cab nearing them, praying it stops so John will get distracted. "It's nothing, I was just-"

"Yes."

Sherlock's hand drops out of the air and he turns to John.

"_Yes_, Sherlock. I meant it." John shifts on the pavement, frowning out at the traffic. "I meant every fucking word. You're _my_ goddamn Alpha."

Sherlock tries to hide his grin but it's irrepressible, pride and happiness spreading through his chest and almost choking him, making him laugh out loud. John snorts, shaking his head at him, but as they climb into the cab, he thinks John looks, if not entirely more at ease, at least a little less guilty.


End file.
